High‐Efficiency Deep Blue OLEDs With Hot Exciton Materials as Emitters and Hosts

Abstract Achieving highly efficient deep‐blue emissive materials with Commission Internationale de l'Eclairage (CIE) coordinates approaching BT.2020 standard remains a significant challenge in organic light‐emitting diodes (OLEDs). Here, three novel deep blue emitters (namely PAF, PAFN, and PAPF) are developed through twisting substitution of anthracene with phenanthridazole unit and dibenzofuran derivatives. All three materials demonstrate efficient hot exciton characteristics, featured by efficient reverse intersystem crossing from high‐lying triplet states to singlet states, which is conducive to harvesting the triplet excitons in OLED applications. Detailed photophysical analyses indicate that the lowest singlet state of these materials is a localized excited state, ensuring highly efficient deep‐blue emission. The non‐doped OLED based on PAPF exhibited deep‐blue emission with a maximum external quantum efficiency (EQE max ) of 8.6% and CIE coordinates of (0.150, 0.057). The binary doped OLED with PAPF as host and organoboron‐based fluorophore as guest achieved an EQE max of 10%, with a narrow full width at half maximum of 18 nm. It is also worth noting that an exceptional efficiency and minimal roll‐off (EQE = 9.0% at 1000 cd m − 2 ) is realized in the current binary host‐guest system. This study provides valuable insights into developing efficient wide‐bandgap emitters for stable, high‐performance OLEDs.